Process for the separation of valuable organic compounds from desugarized molasses and vinasse



PROCESS FOR THE SEPARATION OF VALUABLE ORGANIC COMPOUNDS FROM DESUGARIZED MOLASSES AND YINASSE No Drawing. Application October '15, 1953, Serial No. 386,379

Claims priority, application Netherlands lune 25, 1953 Claims. (Cl. 260-32 63) It is known that by far the greater part of the nitrogcnous compounds present in sugar-containing juices accumulates in the residual liquid (molasses and vinasse). Several of these compounds have cons derable value,

lsuch as amino ,acids, e. g. glutamic acid, which are pres ent in the form'of alkali salts, betaine, and aconit1c ac d.

Molasses is formed during the production of sugar from sugar cane or from beets; vinasse is the residual liquid formed during the fermentation of carbohydrate-containing juices, for example, sugar beets, Jerusalem artichokes and glutamic acid, are first retained in the cation exchanger, but that, upon continued treatment, they are replaced by inorganic cations. In this way it was not possible to .obtain these compounds practically free from inorganic constituents. Certain expedients have therefore been applied. Thus two cation exchangers were placed one behind the other. in the first are initially held the valuable nitrogen compounds, which are subsequently replaced by the inorganic cations; the liquid then flowing ofi is passed through a second cation .ex-

changer; the amino acids and the like are then caught in the latter. It is also possible to charge the first cation exchanger only incompletely with the nitrogen compounds, so that they are not replaced by the inorganic ions. In both cases eluation is effected, for example,

with dilute ammonia. These processes are uneccnomical and it is difficult or impossible to obtain the eluate tree from ash forming material. 7

To this must be added the circumstance that for the ,ion exchange the molasses has to be purified, Since otherwise the filters will soon become clogged by substances of-widely varied nature, such -as pectins, proteins-mucous coupling products of sugar and amino acids.

If all or part of the sugar is removed from the molasses, the valuable compounds are found in the residual liquid. This removal of sugar can be efiected in various Ways, inter alia, by fermentation of the sugar or by the precipitation of the sugar in the form of saccharates by means of an alkaline earth metal oxide. In both these cases a highly diluted residual liquid is left behind.

Now the invention relates to the separation organic compounds from the residual liquid.

It has been found that this can be done etlectively by condensing this residual liquid, diluting the viscous liquid of valuable thus obtained with an organic liquid miscible with this r;nass or with a mixture of such liquids, diluted with water or not, adding, either in admixture with this grgan'ic liquid or separately, an acid whose salts with thelcations present in molasses or vinasse are dififi'cu'ltly soluble or insoluble in the mixture, separating the precipiconsiderably more.

2 tate from the liquid, expelling the organic liquid by evaporation, and passing the remainder through one or more ion exchangers.

Although the new process is not confined to a nnmmum degree of condensation, it is desirable to take the Water content as low as possible; any precipitate of inorganic salts that may be present can be filtered oil intermediately. In general the specific gravity should be 1.2-1.4; this means a water content of about 40-25%.

Methyl alcohol in particular is suitable as organic liquid; other liquids that may be used are, for example, dilute ethyl alcohol and dilute acetone. The quantity of the organic liquid or of the mixture of organic liquids may vary within wide limits. In practice no more than 2 kg. of organic liquid .per kg. of condensed residual liquid will usually be used, since a larger ratio does not cause the process to proceed any more satisfactorily. .If too small a quantity of the organic liquid is used, the viscosity of the mixture remains too great for the separation of a precipitate. By means .of these data it is possible to choose the requisite quantity of the liquid to be added. In general it will sufiice to use about 0.6-2 kg. of organic liquid per kg. of condensed residual liquid; the prpportion by weight of condensed liquid to organic liquid that is preferably used is 1:1.

Acids that may be used are, for example, sulphuric acid, sulphurous acid or phosphoric acid; for practical purposes sulphuric acid was found very suitable. The

quantity of acid that is added may also vary within very wi limits- .In ny c s t m xt e s u b i ifi until a pH below about 6 has been attained. It is best to add such a quantity of acid that the pH is between 3.5 and 1, preferably about 3. 'It is quite safe to acidity to an even lower pH, but this is practically useless; moreover, some amino acids might then precipitate. The end in view is to precipitate all sorts of undesirable substances, including the salts. The latter precipitate practically completely at pHi-B, while other harmful substanPQs will also suficiently precipitate in that case.

The precipitate is separated from the liquid. This can be done by difierent methods, which need not be specified here, since they are sufliciently known in the art. The precipitate formed by addition of the acid can 'be removed, e. g. filtered off, at ordinary temperature. It has, however, been found that the removal of the precipitate can be appreciably accelerated by causing the precipitate .to form at a temperature above room temperature, or by heating the liquid with the precipitate .to temperatures above room temperatureflhen cooling approximately to room temperature, and subsequently bringing about the separation of precipitate and liquid. Even a slight heating of the liquid, or of liquid and precipitate, to, say, 30-35 ,C. will subsequently give rise to an appreciably increased rate of filtration. With continued raising of the temperature .thisrate is increased Little is to be gained, however, by raising .the temperature beyond- .C. For practical purposes a temperature of 4050 C. was found-to be sufilcient.

After the removal .of the precipitate a clear, homogeneous liquid is left behind, in which the various valuable compounds are present.

' After evaporation of the organic liquid, a perfectly clear liquid has been obtained, which, if vnecessary z ifter dilution with water, can be very satisfactorily percolated th ou 10. nge

exchanger. This is possible here because the organic acids have been set free. In practice the liquid is preferably diluted to about 20-30 Br., and then percolated directly through the anion filter. This method has the advantage that in this filter the organic compounds, such as glutamic acid, pyrrolidone-carboxylic acid, and, in the case of cane sugar molasses, aconiticacid, are held and thus separated from the betaine. The eluation may take a. lizes after cooling; there is obtained 0.09 part by weight.

' The other portion is condensed without any previous place in the known manner, e. g. with dilute ammonia or with dilute hydrochloric acid. Thus the ammonium salts or the muriatic acid salts of the organic acids are obtained in solution. If pyrrolidone-carboxylic acid is present, the concentrated solution can be hydrolysed, for

example, with addition of concentrated hydrochloric acid or alkali. i

Preferably the liquid flowing off from the anion exchanger is passed through a cation exchanger; the betaine is then held in thelatter. This may be eluated with an acid, a. g. with dilute hydrochloric acid, or .with a base, f e. g. dilute ammonia. After concentration of the solution, the HCl' salt of betaine or, when the eluation has been made with a base, e. g. with ammonia, the betaine itself crystallizes. This has the advantage that the cations have already been removed, so that there is no riskof the betaine being replaced by other cations.

Example I Two parts by weight of vinasse (originating from fer- I mented molasses) condensed to a water content of 37% are mixed with 2 parts by weight of methyl alcohol until a homogeneous liquid has been obtained. 028 part by weight of concentrated sulphuric acid is added; the pH of the liquid is 3. There is formed a precipiate of sul- 'phates,.mainly potassium sulphate,while proteins and 'pectins also precipitate. This precipitate is removed by filtration, and the methyl alcohol is distilled off. 'After dilution to about Brix, the perfectly clear filtrate is percolated through an anionexchanger; in the latter the organic nitrogen compounds; such as glutamic acid and pyrrolidone-carboxylic acid, are held. After the percolation the liquid has become neutral, while as organic 'nitrogen compound betaine alone is mainly present therein..

The absorbed material is eluated with dilute ammonia;

the eluate contains the organic nitrogeneous acids in the form of NH; salts. The solution is evaporated, with addition of NaOH, as a result of which the N53 escapes; this can be recovered. The organic acids are now present in the solutionin the form of Na salts. With additionof' more NaOH it is now subjected to alkaline hydrolysis with a view to opening the pyrrolidone ring. After acidification to pH 2 with concentrated hydrochloric acid the NaCl is filtered ofiand the liquid is adjusted to pH 3.2.

Glutamic acid now crystallizes. 0.091 part by weight is thus obtained.

, Example H Two parts by weight of vinasse (originating from A total quantity of fermented molasses) condensed to a water content of- 40% are mixed with a mixture of 2 parts by weight of 85% ethyl alcohol and 0.32 part by weight of 96% sulphuric acid. The pH is 2.9. The precipitate of salts and colloidal substances thus formed is filtered oiiand the ethyl alcohol is removed by distillation. The remaining" clear liquid is percolated through an anion filter, after dilution to 30 Br. The organic nitrogen compounds that are held are eluated .with dilute HCl. After evaporation of the eluate solution and hydrolysis, of the pyrrolidonecarboxylic acid by addition of concentrated'I-ICl', the HCl salt of glutamic acid crystallizes. A total quantity of 0.12 part by weight of glutamic acid HCl salt is obtained. V The liquid flowing oif from the anion filter is divided into two portions. through a cation filter. V Aftereluation' with dilute NHsOH and condensation of theeluate, betaine crystal- One portion is percolated treatment and mixed, for example, with ground beet pulp, as a result of which a strewable powder is obtained, which is immediately suitable for admixture in cattle food.

Example III.

Two parts by weight of Steffens liquid condensed to a water content of 35% are stirred together with'2 parts by weight of methyl alcohol until the mixture is homogeneous. After addition of 12% by weight of concentrated sulphuric acid, caluculated on the condensed liquid, a precipitate is formed, which is removed from the liquid. The pH is 3. The methyl alcohol isdistilled olf, and the remaining clear liquid is percolated through an anion filter after dilution to about 30 Brix. The procedure is further as described inExample I.' A total quantity of 0.15 part by weight of glutamic acid is obtained.

Example IV Five kg. of molasses are mixed with 5 kg. of methyl alcohol and the mixture is heated to 50 C. There is added 6% by weight of concentrated sulphuric acid, calculated on molasses. Then the mixture is rapidly cooled to room temperature. The precipitate formed'is then sucked off in a Biichner funnel with a filter area of 5 dm."*; the pressure below the filter is 40 cm. of mercury. The filtration time is 5 minutes. If the precipitate is formed and sucked off at room temperature, the filtration time is 15 minutes. The separation of the valuable compounds from the filtrate can take place in the same manner as described in the preceding examples.

Iclaim: 1. Process for the recovery of valuable organic compounds firom a solution of the group consisting of filtrates from the treatment of molasses with alkaline earth metal oxides and vinasse which comprises concentrating the solution, mixing the resulting concentrated solution with a mutually soluble organic liquid chosen from the group consisting of methyl alcohol, ethyl alcohol and acetone in an amount of from 0.6 kilograms to 2 kilograms per kilogram of said concentrated solution, acidifying the resulting mixture to a pH between 6 and 1 with an acid whose salts with the cations present in the mixture are substantially insoluble in the mixture, separating the resulting precipitate'from the liquid part of the resulting mixture, subjecting the separated liquid to partial evaporation to remove said organic liquid therefrom, passing'the residual liquid through an ion exchanger and recovering absorbed material from said ion exchanger. 2. Process as defined in claim 1 in which the solution is first concentrated to a water content of from about 25% to about 40%.

removal of. organic liquid by evaporation theresidua'l liquid 'is diluted with-water and'passed first through a cation exchanger and then through an anion exchanger. 4. Process as defined in claim 1 in which after removal of the organic liquid by evaporation the residual liquidis "diluted with water and passed successively throughan anion exchanger and a cation exchanger. 5. Process as defined in claim 1 in which .of the organic liquid by evaporation-the residual liquid is diluted with Water to form about 20 to about 30. .Brix. 6. Process as defined in claim 1 in which the solution is concentrated to a water content of from 25% to 40%, the organic liquid is methyl alcohol and the acid is sullflll'lt. acid.

' 7. Process as defined in claim 1 in which the solution is concentrated to a Water content of from 25% to 40% and mixed with one part by weight of methyl alcohol per part by weight of concentrated solution, sulfuric acid is added to the mixture in quantity sufficient to establish a pH of from 1 to 3.5 and the residual liquid after the removal of the methyl alcohol therefrom by evaporation is after removal 5 diluted with water to frem 20 to 30 Brix and the diluted liquid is passed threugh a cation exchanger.

Process as defined in claim 1 in which the solution is concentrated to a Water content of from 25% to 40% and mixed with from 0.6 to 2 parts by weight of methyl alcohol per part by weight of ccncentrated solutien, sulfuric acid is added to the mixture in quantity sufficient to establish a pH of from 1 to 3.5 and the residual liquid after the removal of the methyl alcehol therefrom by evaporation is diluted With Water to from 26 to 3G Bi: and the diluted liquid is passed successively through an anion exchanger and a cation exchanger.

9. Process as defined in claim 3 in which organic carboxylic acids and betaine are recovered from the cation exchanger and pyrrolidone carboxylic acid is recovered from the anion exchanger.

10. P-recess as defined in claim 4 in which organic carboxylic acids including pyrrolidone carboxylic acid are recovered from the anion exchanger and hetaine is recovered from the cation exchanger.

References Cited in the file of this patent UNITED STATES PATENTS 2,375,164 Bennett May 1, 1945 2,519,573 Hoglan Aug. 22, 1950 2,688,037 Hoglan Aug. 31, 1954 2,713,592 Hoglan July 19, 1955 

1. PROCESS FOR THE RECOVERY OF VALUABLE ORGANIC COMPOUNDS FROM A SOLUTION OF THE GROUP CONSISTING OF FILTRATES FROM THE TREATMENT OF MOLASSES WITH ALKALINE EARTH METAL OXIDES AND VINASSE WHICH COMPRISES CONCENTRATING THE SOLUTION, MIXINGH THE RESULTING CONCENTRATED SOLUTION WITH A MUTUALLY SOLUBLE ORGANIC LIQUID CHOSEN FROM THE GROUP CONSISTING OF METHYL ALCOHOL, ETHYL ALCOHOL AND ACETONE IN AN AMOUNT OF FROM 0.6 KILOGRAMS TO 2 KILOGRAMS PER KILOGRAM OF SAID CONCENTRATED SOLUTION, ACIDIFYING THE RESULTING MIXTURE TO A PH BETWEEN 6 AND 1 WITH AN ACID WHOSE SALTS WITH THE CATIONS PRESENT IN THE MIXTURE ARE SUBSTANTIALLY INSOLUBLE IN THE MIXTURE, SEPARATING THE RESULTING PRECIPITATE FROM THE LIQUID PART OF THE RESULTING MIXTURE, SUBJECTING THE SEPARATED LIQUID TO PARTIAL EVAPORATION TO REMOVE SAID ORGANIC LIQUID THEREFROM, PASSING THE RESIDUAL LIQUID THROUGH AN ION EXCHANGER AND RECOVERING ABSORBED MATERIAL FROM SAID ION EXCHANGER. 